** Brazilian Rare Earths BRE.AX soars as much as 10.4% to A$1.965, highest since February 21

** Stock set for biggest intraday pct gain since April 1

** Mineral explorer signs deal with Rio Tinto Brazil to amend 2023 agreement, which gave co rights for $9.3 million and an additional milestone payment of $40 million

** Says the $40 million payment now replaced with fixed royalty of $1.00 per wet metric tonne of bauxite sold

** Stock set for third consecutive session of gains

** BRE last up 8.3%, trimming YTD losses to ~18.3%

(Reporting by Manasi Dasa in Bengaluru)

((Manasi.DasaSundeep@thomsonreuters.com;))